matchers/not.go

package matchers

import "github.com/onsi/gomega/types"

type NotMatcher struct {
	Matcher types.GomegaMatcher
}

func (m *NotMatcher) Match(actual interface{}) (bool, error) {
	success, err := m.Matcher.Match(actual)
	if err != nil {
		return false, err
	}
	return !success, nil
}

func (m *NotMatcher) FailureMessage(actual interface{}) (message string) {
	return m.Matcher.NegatedFailureMessage(actual) // works beautifully
}

func (m *NotMatcher) NegatedFailureMessage(actual interface{}) (message string) {
	return m.Matcher.FailureMessage(actual) // works beautifully
}